Above: High-altitude aerial photography, Hudson River, NY.
Below: Same area on a NOAA nautical chart. Comparing these sources, created at different times, provides information on the rate of change in the coastal zone, which aids in the design of coastal zone mapping projects. Click image for larger view.

Since the late 1930s, high-resolution, georeferenced aerial photography
for defining the nation's 95,000-mile
shoreline has
been a responsibility of
the National
Geodetic Survey (NGS), part of NOAA's National Ocean Service (NOS). Metric aerial photographs are the primary source
material used for creating coastal survey maps and digital cartographic feature files. These data sets, in turn, provide
data for producing NOAA nautical
charts.

Determining the accurate location of the shoreline is extremely important because it is used as a
source to define the boundaries between private, state, and federal ownership and jurisdictions, including the territorial
sea and the Exclusive Economic Zone. Tidal datum lines derived from the NOAA nautical chart are a source used to determine
such marine and maritime limits. These photographs have many other uses as well, including coastal management, waterfront
development, natural resource identification, water-depth measurements, topographic mapping, sea-bed characteristic mapping,
and location of features or obstructions to ensure the safety of marine and air navigation.

Products and Mission

The primary aerial photographic product is a 9x9-inch color photograph, usually at scales from 1:10,000 to
1:50,000. More than 500,000 photo negatives, dating from 1945 to the present year, exist in NOS archives and are maintained by NGS.
Aerial photography surveys are conducted on varying time cycles, depending on the amount of change caused by human or natural
forces. Other types of photographs include panchromatic, false-color infrared, and black-and-white infrared.

Photography is acquired when weather conditions, sun angle, and, when applicable,
water levels are optimal to ensure that photographs will be
suitable for a variety of purposes using standard photogrammetric
techniques. NOS now manages the majority of its mapping projects
through contracts with private mapping firms. These firms are
responsible for every phase of project completion, from acquiring
aerial photographs to generating digital cartographic feature
files.

Digital aerial photography showing devastation in Ocean Springs, Mississippi. This imagery was acquired by NOAA on August 30, 2005, one day after Hurricane Katrina slammed the region.

The NOAA Coastal Shoreline Mapping Web site provides the ocean and coastal resource management community with data and information related to shoreline mapping. It contains links to
digital data, references pertaining to the legal and technical aspects of the shoreline, and organizations that are working to support the collection of shoreline data for the
coastal component of the National
Spatial Data Infrastructure, a nationwide effort to improve the use of geographic data within the United States.

NOS scientists used LIDAR images to aid recovery efforts at the World Trade Center disaster site. The images allowed building and utility engineers to locate original foundation support structures, elevator shafts and basement storage areas, and pinpoint digging and recovery efforts.

Related Projects and Technologies

A major project involving aerial photography and shoreline mapping is
the Topographic
Change Mapping project. This project involves acquiring high-resolution topographic data through remote-sensing technologies for coastal resource managers.
Topography is the general shape or form of land surface, including its relief and arrangement of features.
NOAA Coastal Services
Center (CSC) is significantly involved in this project.

Land cover represents another important data resource for those who manage coastal resources. Land-cover maps document how much of a region is covered by forests, wetlands, impervious surfaces, agriculture, and other land and water types. The maps are created using remotely sensed data, which include both satellite and airborne imagery. No other technology provides a better big-picture view of a region.

Most of the nation’s coast is included in the baseline dataset. By comparing maps from various years, users can see how the land surface changes over time. This information not only helps when gauging current conditions, but also plays an important role when crafting policies that direct future land-use decisions.

NOS analyzes high-resolution satellite imagery and high-altitude aerial photography to evaluate coastline changes. Digitally overlaying the imagery (shown in green) with the charts developed earlier reveals changes in shoreline features along the San Diego coast.

Educational Resources

Determining the accurate location of the shoreline is extremely important because it defines the boundaries between private, state, and federal ownership and jurisdictions, including the territorial sea and the Exclusive Economic Zone.

A major project involving aerial photography and shoreline mapping is the Topographic Change Mapping project.